Untreated Bipolar/BPD sibling falsely tells her family I steal

My eldest sibling (18 years older- so not raised together) has been diagnosed by Mayo as bipolar with BPD - she, however feels they are wrong and refuses all treatment. As a family we are used to her always being mad at someone ( it alternates) or storming off from various family gatherings (although we’re never quite sure what triggers it) and have adapted ( AKA- while around her on a bad day we tread carefully ). She is smart, creative and a hard worker. She does complain a lot - relentlessly the victim of something ( usually her own choices) or someone ( she seems to think everyone is discriminating against her for being an older woman). Recently I found out that even though I go to lunch with her occasionally and she drops by for visits and texts me a few times a week - she has been at the same time telling her family ( over and over for months) that I am sneaking into her house to steal things when she is out ( huh?!?) . I happened to oversee a text this past weekend that she sent her daughter telling her she just couldn’t handle the stress of it ( note: I’ve been to her home twice this year by invitation). My niece won’t tell me more as she says it would only upset me and they all understand she’s lying ( she finally admitted that most things were in regards to how terrible my adult children are, as humans and to me - FALSE! I have a close and loving relationship with my kids and they are kind to me ). I could go on with examples- but you get the point. Kind to my face and even seeking me out while saying terrible things about me behind my back ( right when I was telling everyone how great she was doing and how much I enjoyed her company ). I understand she can’t necessarily control it and I understand that she may not even be aware of how illogical the things she accuses me of are - so I try to be patient and kind. But do I really need to be in contact with someone who on the best of days mostly talks AT me and must I tolerate such the lies - no acknowledgment or apology will ever come. Last I texted her she said her kids made the whole thing up …. I saw the text as I was holding my nieces phone when it came thru ). She’s now FURIOUS at her daughter. I love her - but the stress she brings into my life is exhausting and hurtful. This is the 3rd time she accused me of stealing , but first time saying that a sneak into her home ( she also tells people I flip houses for a living - NO, I simply moved and that I had to move or my daughter was threatening to leave the state if I didn’t ( this is NOT the case at all - yet this lie she tells lots of folks… it’s so confusing!) . She is very intelligent and I fear that by living in a small town near her that she could obviously unjustly hurt my reputation. The bigger concern is - can the type of behaviors she is exhibiting towards me become dangerous? I am seriously wondering if I should move ( AKA: leave the state). Am I overreacting? I think yes - yet I am so incredibly unsettled by all this. I can tell you right now that she will never get help as she doesn’t have any problems ( just ask her ). Her diagnosis came from a 72 hour lock up situation from threatening to harm herself ( she says this often when she thinks her kids don’t love her - but it’s actually when they won’t abide by her demands) The one time I got her into a therapist, about 5 years ago, was to help her with the grief of her husband passing - but the counselor “fired her” after two visits ( awesome and qualified counselor I might add ). She can turn on the lovely and kindly ways as fast as the annoyed and demanding ways- and most people only see one side. ( … until!) Is this manipulation or has she no choice ? I don’t know how to handle this in a way that protects me ( and my stress level) while not aggravating her stress level ( she already has very high blood pressure). Does anyone have any ideas ?💙 I have read all the bipolar books and Walking on Eggshells. I think I need to truly walk away- but I’d feel so incredibly guilty as I can’t imagine anyone would behave like this by choice. And she’s my sister - and getting old… ARG! The dilemma of it all. If you have read to the end - I truly thank you.